1. Field of the Invention
The present invention relates generally to aircraft cargo handling. More particularly, the invention concerns an apparatus for protecting the sill of an aircraft cargo door against damage during cargo loading and unloading.
2. Discussion of the Invention
Transport of cargo by aircraft has increased dramatically over the past several years. As the size of aircraft has increased so has the size of cargo containers and pallets used to transport the cargo to the aircraft making them most cumbersome and difficult to handle and to load into the aircraft cargo holds.
Typically, the cargo to be transported by the aircraft is loaded into the aircraft cargo hold through door openings usually provided in the sides of the aircraft. The door openings are normally closed by doors of complex design which, for safety reasons, must tightly seal within the door opening. Damage to the door opening, and especially to the door sill must be strictly avoided because even slight damage to the sill, or to the door closure or locking spools, which maintain the door in a closed and locked position, can prevent proper closing of the door.
Because the sill of the door opening can easily be damaged during movement of the large cargo containers and pallets into the cargo holds, several types of devices have been suggested in the past to bridge the door sill and protect it from damage. As a general rule, these prior art devices are somewhat crude, bulky and often difficult to handle and store. In some instances, the devices are stored within the cargo hold, thereby taking up valuable cargo space, and in other instances, after the cargo has been loaded they are simply thrown from the aircraft door onto the tarmac below. When thrown from the aircraft, the bridging devices can easily be damaged, or misplaced and lost.
A U.S. Pat. No. 5,312,071 recently issued to Eilenstein-Wiegmann, et al. discloses a more sophisticated mechanical device for protecting an aircraft door sill. This device includes a cover plate having an outwardly extending edge that is supported by a support linkage that includes a support section, a bracing section, first, second and third journals and a foot for releasably cooperating with a holding member that is secured to the aircraft body.
The apparatus of the present invention uniquely overcomes the drawbacks of the prior art sill protecting devices by providing an elegantly simple, lightweight, compact and easy to use sill protector that is made up of a minimum number of component parts. The cover plate of the device is uniquely supported by the existing door closure or locking spools of the aircraft thereby protecting the spools against damage while at the same time greatly simplifying the construction and operation of the sill-protecting apparatus.